The Promise
by RMBlythe
Summary: "Steve? Don't… Don't leave, okay?" Steve smiled, "Never, Buck. I'm with you till the end of the line, remember?" "Yeah. I remember." Time. Experiments. Distance. Nothing will separate them. A promise spans nearly 80 years and it's one Steve Rogers and James Buchanan Barnes refuse to break.


_**I read a quote that said best friends are one soul inhabiting two bodies (something like that), and that just really strikes me as perfect for Steve and Bucky (neither of whom I own). There is a bond so strong between them, and I love exploring that. This is my first adventure into the Marvel fandom (which I also don't own). Each chapter will be a stand alone one-shot, exploring the relationship between the two by paralleling their lives pre- and post-serum. Enjoy! Let me know what you think!** **  
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* * *

 _ **New York, 1939**_

Before Sarah Rogers died, she made Bucky promise that he would always be there for Steve. Without a moment's hesitation or a second thought, he'd said yes. Of course he would. They had been friends for so long. Their memories were so entwined that just the thought of trying to untangle them was enough to give someone a migraine. They had always been together, so where else would he be other than at Steve's side? As far as Bucky was concerned, that was where he belonged and that was where he'd stay.

But then Sarah said something Bucky never could quite shake. "He's so lucky to have you, James," she'd smiled, her eyes welling with tears as she took his hand in hers and gave it a pat. "I don't know where he'd be without you. He is so lucky."

Her words haunted him now as he sat beside Steve's bed, watching his chest rise and fall with each wheezing breath that shuddered through him. "Lucky" was not a word he would used to describe Steve, even though nearly everyone else did.

When he paid the rent each month, their landlady would say, "He is so lucky to have a friend like you."

The grocer a few blocks over always remarked, "Pure luck, that kid finding you, that's what it is. Pure luck."

And then there was that gang of teenagers who had been about to mug Steve until Bucky came along and sent them running. "You're damn lucky your friend came around to save your scrawny ass!" they had shouted back.

Bucky was just about to take off after them when a slender hand gripped his elbow. Steve was looking up at him with a fat lip and a black eye. "Don't do it, Buck. They're just looking for trouble, and you gave it to them. So let's go home."

He didn't say anything, too busy staring at Steve's bruised face and thinking of what he'd like to do to those punks.

Steve had given him a stern look then. "It's not worth it, Bucky. It's done. Let's go home before my eye swells completely shut."

Bucky had scoffed and Steve smirked as they made their way back to the apartment. If Steve noticed Bucky walked a bit closer or kept a sharper eye out, he hadn't said anything.

With a sad smile, Bucky reached out to place a damp, cool cloth on Steve's forehead, brushing his hair back and out of the way as he did. "You're not lucky, Steve," he said softly. "I am."

How many times had Steve stopped him from taking it that one step too far? Steve was always willing to jump into a fight, hell, he'd even pick one, but only if it was for the right reasons. Fight for justice. Fight for fairness. Teach them the lesson they needed to learn, then let it go and move on.

Bucky could never do that. Bucky fought for revenge.

Sometimes, he was afraid of who he might have been, who he might become if anything happened to Steve. The thought was terrifying, if he were completely honest.

He shook his head, focusing instead on Steve. Sweat poured from his body, but Bucky was hesitant to take the light quilt off him for fear that he would start shivering again. His heartbeat was erratic and quick. He could see it jumping at the pulse point on his neck. He'd started coughing up blood today too. Not much, and it was nothing that hadn't happened before, but still… Last time it ended with a trip to the hospital. Bucky didn't know how many close calls the kid had left.

He sighed, laying his head down so his forehead was resting on the edge of the thin mattress. "Don't do this," he found himself begging, his voice no more than a whisper even though there was no one else to hear him but Steve. "You can't do this to me, pal. I need you," he admitted, fingers curling into a tight fist. "I don't wanna see me without you. I'm scared, Steve. I don't…" his breath caught in his throat. His eyes stung with tears and the sob in his chest was making it difficult to breathe.

A hand covered his, holding on to it with everything he had. Bucky's head snapped up, wide eyes landing on Steve's exhausted smirk. "You're such a jerk," Steve rasped, his voice hoarse after barely having used it in the last four days. "I'm dying of pneumonia and all you can think about is yourself.

Bucky huffed a laugh, blinking back his tears. Now wasn't the time for them. "Only you would get pneumonia in the spring, you little punk."

Steve laughed softly, closing his eyes again.

"Steve?"

He hummed, opening his eyes once more.

"Don't… Don't leave, okay?"

Steve smiled. "Never, Buck. I'm with you till the end of the line, remember?"

"Yeah. I remember."

* * *

 ** _New York, 2014_**

"I'm with you till the end of the line."

The Winter Soldier felt as though he'd been knocked about a hundred feet. Why did that sound so familiar? What was that? There was a blonde kid. A busted, fat lip. A clear blue eye nearly swollen shut. _Don't do this…_

Choking breaths. Blood. A fever. Begging. _I'm scared Steve…_

 _Steve._

His chest felt tight. Steve! Oh God, what had he done?

Before he could do anything, before he could possibly think of something to say, there was a menacing groan and resounding crash as a part of the ship fell, shattering the window they had been fighting on and taking Steve with it. Bucky watched in horror as Steve fell surrounded by shards of glass and burning, twisted metal. What had he done?

The heat of the exploding aircraft blazed against his back, but he could only watch as Steve fell. The smoke nearly swallowed him, but he could still see when he hit the water. Already, the memories were starting to fade again, but he fought to hold on to the image of that blonde kid, the feeling of a slender hand tugging on his arm, holding him back, grounding him…

He couldn't explain why, but he needed this guy to come back up. To surface and breathe. To live. Maybe that's why, when he didn't, the Winter Soldier dove from the ship straight into the water below.

He grabbed him. Clutching a fistful of the red, white, and blue uniform that something in the back of his mind was telling him was important, he dragged him to the water's edge. He stood watching over him for a moment. He wasn't sure what he was waiting for, but… There. Water trailed from his blood-stained lips and he took a shallow, choking breath. Good. He was alive.

The Winter Soldier looked around. If they saw him save him… His breath caught when he thought of what they might do. He couldn't go back. He wouldn't go back. Captain America- Steve- had called him Bucky. James Buchanan Barnes. Maybe he couldn't be the same Bucky again, but he wasn't going to be the Soldier anymore.  
With one last check over his shoulder, he staggered away, resisting the urge to go and check on the man behind him one more time.

Hospitals are quiet at three o'clock in the morning. He timed it just right. Only a few nurses on duty and Romanov had stepped out only two minutes ago to get coffee.

He didn't make a sound as he made his way down the hall and slipped in to the dark private room. He stood inside the door for a minute or so, just watching the man in the hospital bed. He didn't move or make a sound. Just watched. It was loud enough in his head anyway. Orders shouted in Russian. Commands barked in English. His own screams echoing in his ears. They were quieter here though, he realized. And the closer he got to the bed where the man lay- Steve, a gentle voice reminded him amidst all chaos- the quieter the voices became.

He took a few hesitant steps forward, not thinking about what he was doing until he felt his thighs pressing against the edge of the bed. Not knowing what else to do, he sat in the chair Romanov had left empty. Reaching out, he ran a hand through Steve's blonde hair with a more gentle touch than he knew he was capable of. He didn't have the words to explain why, but being by Steve's side like this felt right. Like he was supposed to be there. And that was something he couldn't remember feeling in a long time. He may not know who he was, but Steve seemed to. It was as good a place to start as any, he supposed.

But he knew he couldn't stay here. Not for long, at least. Not yet.

"Buck?"

At the sound of the familiar rasp, Bucky focused back on Steve's face where glassy blue eyes stared up at him.

"Yeah?"

Steve's eyes were already drifting closed again, but he fought against it. "Don't… Don't leave, okay?"

Bucky shook his head, saying softly, "I'm with you till the end of the line."

He didn't know if he'd be able to keep that promise, but the smile on Steve's face as he drifted back to sleep made him more determined than ever to try.


End file.
